<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding:0;
            list-style: none;
        }
        body{
            background: #04041c;
        }
        h1{
            color: #fff;
            text-align: center
        }
        ul{
            width: 620px;
            height: 620px;
            margin: 40px auto;
            overflow: hidden;
            position:relative;
            /* background: #fff */
        }
        ul li{
            border: 2px solid #394057;
            position: absolute;
            top: 50%;
            left: 50%;
            width: 200px;
            height: 200px;
            transform: translate(-50%,-50%);
            border-radius: 50%;
            animation:move 3s linear infinite;
        }
        ul li span{
            width: 12px;
            height: 12px;
            border-radius: 50%;
            background: green;
            display: inline-block;
            position: absolute;
            left: 50%;
            margin-left: -6px;
            top:-6px;
        }
        ul li:nth-child(1){
            width: 60px;
            height: 60px;
            background: #cc9900;
            box-shadow: 0 0 50px #cc9900;
            border:none
        }
        ul li:nth-child(2){
            width: 120px;
            height: 120px;
            animation-duration: 2s
        }
        ul li:nth-child(3){
            width: 180px;
            height: 180px;
            animation-duration: 4s
        }
        ul li:nth-child(4){
            width: 240px;
            height: 240px;
            animation-duration: 6s
        }
        ul li:nth-child(5){
            width: 300px;
            height: 300px;
            animation-duration: 8s
        }
        ul li:nth-child(6){
            width: 360px;
            height: 360px;
            animation-duration: 10s
        }
        ul li:nth-child(7){
            width: 420px;
            height: 420px;
            animation-duration: 12s
        }
        ul li:nth-child(8){
            width: 480px;
            height: 480px;
            animation-duration: 13s
        }
        ul li:nth-child(9){
            width: 540px;
            height: 540px;
            animation-duration: 14s
        }
        ul li:nth-child(10){
            width: 600px;
            height: 600px;
            animation-duration: 15s
        }
        @keyframes move{
            0%{
                transform:translate(-50%,-50%) rotate(0)
            }
            100%{
                transform:translate(-50%,-50%) rotate(360deg)
            }
        }
    </style>
</head>
<body>
    <h1>我的太阳系</h1>
    <button id='add'>加快</button>
    <button id='remove'>减慢</button>  
    <ul>
        <li></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
        <li><span></span></li>
    </ul>
</body>
</html>
<script>
    var oLis = document.getElementsByTagName('li');
    function change(n){
        for(var i =0; i < oLis.length;i++){
            oLis[i].style.animationDuration = i*n + 2 +'s';
        }
    }
    add.onclick=function(){
        change(2)
    }
    remove.onclick = function(){
        change(1)
    }
    
</script>